Deer crossing a two-lane highway
The number of cars hitting animals surged last year in California. Could installing more fencing and crossings like some Red States have done help reduce the carnage? Stringer/Reuters

Crashes between cars and critters are up in California, particularly in the Bay Area. What can transportation departments do?

In the San Francisco Bay Area, high-speed, high-volume traffic and seasonal migrations have created a maelstrom of animal-driver carnage. A motorcyclist was recently killed when he struck a large deer. A cyclist flying down a hill smacked into a deer and suffered a concussion and memory loss. The region ranks among the worst for wildlife-vehicle collisions in California, according to a report from UC Davis.

The number of drivers smashing into animals—deer are by far the most common victims, but there are also coyotes, bears, elk, mountain lions, and wild pigs—are up in California. The university’s researchers counted 7,831 such incidents in 2016 on highways and major roads, an increase of more than 2,000 over the previous year. These figures are all probably underestimates, as many people don’t report hitting animals and others swerve to avoid them, generating accident reports that often fail to mention wildlife.

Fraser Shilling, one of the authors of the UC Davis report and co-director of the Road Ecology Center, guesses the recent surge in collisions is due to the end of California’s bitter drought, which had starved deer of their preferred foods (delicious forbs!) and withered the vegetation they shelter in to avoid predators.

What might transportation gurus do to stop the local deer—which are everywhere, stalking the scenic hills of Berkeley and wandering onto both the Bay and Golden Gate bridges—from crossing the road and causing havoc?

Shilling has some strong thoughts. “It really depends on how seriously one takes wildlife conservation and driver safety,” he says. “If we manage to think of two things at once—we scratch our heads and pat our tummies and say, ‘We want to protect drivers and wildlife,’ then we need to fence and provide safe passage.”

“If we were to do this at the state level, we would find all these bad places [for wildlife-vehicle collisions] and act on it,” Shilling continues. “That’s the rational decision-making if one were rational in politics. It’s just that we are not on that pathway, we’re sort of in a rest area on this whole issue.”

Problem spots where many vehicles are hitting animals in California are highlighted in red. (UC Davis Road Ecology Center)

Beyond the problem of mass animal fatalities, California’s wildlife collisions dinged society to the tune of $500 million in 2015 and 2016, according to the Road Ecology Center, if you take into account costs like property damage, emergency response, medical bills, and time off work. When hit with enough speed, deer can total cars and break through the windshield, causing grievous injuries to drivers and passengers. In addition, about five people die in the state annually from animal-involved wrecks. This video of a bus hitting a deer illustrates the sheer force of an animal strike—it’s graphic, but in this case the deer seems to have escaped without too much harm.

On some Bay Area highways, notably a 23-mile stretch of Interstate 280 leading through Silicon Valley that saw at least 386 collisions in this two-year period, the cost of these collisions approaches or exceeds $1 million per mile. Shilling estimates the cost on I-280 could be paid for in about half a year by installing wildlife fencing—typically sturdy, 8-foot-tall barricades with square mesh. In this location he’d want to kick it up to 10 feet to repel mountain lions.

The cost of cars hitting animals exceeded $1 million per mile of roadway in parts of the Bay Area for 2015–2016, according to a new analysis. (UC Davis Road Ecology Center)

He’d also like to see underpasses or overpasses installed to give animals safe passage. “In terms of driver safety, this kind of fence and crossing solution is one of the most effective, if not the most effective, method of reducing risk to drivers,” he says. “The effectiveness is usually around a 90-to-95 percent reduction in wildlife collisions with vehicles.” So if it’s that easy, why isn’t California doing more to keep animals out of the way of motorists?

To its credit, state transportation department Caltrans has built some wildlife-crossing infrastructure, such as soon-to-open underpasses for tiger salamanders in Santa Barbara County and deer fencing and an underpass for various critters in Sierra County (check out the lumbering bear traversing it below). While Caltrans says it’s still analyzing the UC Davis report and wouldn’t comment on it, the agency believes it isn’t exactly doing nothing.

A bear walks through a wildlife crossing under California’s Highway 89 this May. (Caltrans)

“We have approximately 50 planned, in-construction, or constructed projects that have wildlife-crossing components as part of their scope,” says Jim Henke, a senior wildlife biologist at Caltrans. “Those components would include wildlife fencing and improvements to culverts and bridges and underpasses, and also standalone structures.”

The problem with getting these interventions up in California is that, in governmental jargon, they need to have a transportation nexus. “The funding has to come from a transportation need,” says Henke, instead of a conservation demand. “If there's a project that triggers a mitigation need for wildlife movement, then that’s where we see an opportunity to install and plan for those types of crossings,” he adds.

That explains why Caltrans is seeking outside ways to construct wildlife crossings, such as partnering with concerned citizens and nonprofits. For a proposed wildlife crossing on Route 101 in Los Angeles County—which has separated habitats for mountain lions, resulting in inbreeding and territorial fighting—the agency hopes to help cover the project’s roughly $60 million price tag through everyone’s favorite modern way of funding: crowdsourcing. This state of affairs infuriates Shilling.

“Considering we have $12 to $15 billion a year in the transportation budget, and we just added another $5 billion with Senate Bill 1 per year, we have a lot of money. It’s just what we choose to spend it on,” he says. Shilling fears California’s transportation officials have adopted the “it’s-not-our-problem” attitude that wildlife collisions are an environmental concern, and need to be solved by an environmental agency. “If it was framed as a driver’s-safety issue I think the imperative would be much greater,” he says. “It's just difficult to get transportation agencies to think of it that way.”

But if California were to suddenly invest massive duckets into protecting wildlife on roads, where should it direct the cash? For answers, it might want to turn toward its neighbors. Utah, Idaho, Nevada, Montana, and Colorado have all installed animal-crossing infrastructure such as underpasses and overpasses, the latter being something that California lacks despite research suggesting wildlife prefer them over tunnels because they’re less dark and noisy. (They’re also much more expensive, however.) Arizona even has an elk crosswalk that implements “military-grade target-acquisition software” to detect animals and activate flashing lights alerting drivers.

“I’m seeing a lot of growth, a lot of momentum in the West,” says Jeff Gagnon, a statewide research biologist for the Arizona Game and Fish Department. “It’s probably as good as it’s been yet. There are enough people that believe in it and enough evidence out there that it works.”

Arizona started getting heavily into wildlife crossings and fences around 2000, mainly for elk and big-horn sheep, and has since logged promising results. “We saw as high as a 97 percent reduction in some areas with elk-vehicle collisions,” says Gagnon. In the 3-mile area with the military-level crosswalk and fences, for instance, the state went from seeing about 12 elk collisions a year to just two in a decade. “So if you extrapolate those numbers, the past 10 years we should’ve had at least 120 accidents, and with the traffic volume increasing, probably more,” Gagnon says.

The “funnel concept” helps animals get across roads unscathed, Gagnon adds. Exclusionary fencing along highways catch and funnel wildlife toward protected “spouts,” or crossings like overpasses and underpasses. You can apply the concept to any kind of creature—erect knee-high fences for lizards, for example, or emulate Christmas Island and build bridges for hordes of migrating red crabs.

Gagnon’s preference is for costlier overpasses because animals might feel less trapped in them compared to shadowy, concrete-walled underpasses. “The concept of the overpass is if you try to make it a continuation of the habitat around it, the animal ultimately doesn’t even know it’s crossing the road,” he says. But more-natural underpasses such as crossings running through valleys and along rivers underneath highway bridges are good options, too. “The underpasses that are really large and have natural slopes work well for a lot of animals,” he says.

Ultimately it’s up to the state to choose the animal architecture it wants. The important thing is that transportation departments do something to prevent these casualties, which can be bloody affairs, particularly when animals travel in herds. Gagnon recalls seeing several accidents that involved vehicles hitting multiple animals at once.

“When someone comes around the corner and their headlights are on, elk and deer will sometimes just stand there and look at you—their night vision kind of locks them up when they get shined on and you can just plow through them,” Gagnon says. “I’ve seen a semi pick out six elk in one swipe.”

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